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Significant New Alternatives Policy Program

Fire Extinguishing and Explosion Prevention Sector

Risk Screen on Substitutes for Halon 1301

Total Flooding Systems in Normally Unoccupied Spaces

Substitute: Dry Sprinkler Powdered Aerosol (DSPA) Fixed Generators

This risk screen does not contain Clean Air Act (CAA) Confidential Business 

Information (CBI) and, therefore, may be disclosed to the public.

1. INTRODUCTION

Ozone-depleting substances (ODS) are being phased out of production in response to a series of 

diplomatic and legislative efforts that have taken place over the past two decades, including the Montreal 

Protocol and the Clean Air Act Amendments of 1990 (CAAA). The U.S. Environmental Protection 

Agency (EPA), as authorized by Section 612 of the CAAA, administers the Significant New Alternatives 

Policy (SNAP) Program, which identifies acceptable and unacceptable substitutes for ODS in specific 

end-uses based on assessment of their health and environmental impacts.

EPA’s decision on the acceptability of a substitute is based on the findings of a screening assessment of 

potential human health and environmental risks posed by the substitute in specific applications. EPA has 

already screened a large number of substitutes in many end-use applications within all of the major ODSusing sectors, including refrigeration and air conditioning, solvent cleaning, foam blowing, aerosols, fire 

suppression, adhesives, coatings and inks, and sterilization. The results of these risk screens are presented 

in a series of Background Documents that are available in EPA's docket.

The purpose of this risk screen is to supplement EPA’s Background Document on the fire suppression 

and explosion protection sector (EPA 1994) (hereinafter referred to as the Background Document). This 

risk screen discusses the potential human health and environmental risks posed by Dry Sprinkler 

Powdered Aerosol (DSPA) generator when used as a flooding agent in normally unoccupied spaces as a 

replacement for Halon 1301. The proposed substitute is anticipated to be used for Class A (ordinary 

combustibles), B (flammable liquids and gases), and C (electrical) fires, pending UL approval. The reader 

is referred to the Background Document for the methodologies and assumptions used to conduct this risk 

screen. 

DSPA generators contain a solid material in pellet form that aerosolizes upon activation. The DSPA 

fixed generators are designed to suppress fires as fixed installations in enclosed areas in all industrial and 

commercial structures and in the transport sector (trains, trucks, cars, and ships) in normally unoccupied 

spaces. The DSPA fixed generators include several models. Table 1 presents the composition of the 

proposed substitute, prior to activation.
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Table 1: Composition of DSPA Generator, Prior to Activation

Constituent (Solids) Chemical 

Formula CAS # Weight Percent

Potassium nitrate KNO3 7757-79-1

Phenol formaldehyde resin C13H12O2 9003-35-4

Cyanoguanidine C2H4N4 461-58-5

Table 2 presents the composition of the post-activation products of the proposed substitute. 

Table 2: Composition of DSPA Generator, Post-Activation

Solid Particles Chemical 

Formula CAS # Weight Percent

Potassium carbonate K2CO3 584-08-7

Ammonium bicarbonate NH4HCO3 1066-33-7

Potassium bicarbonate KHC03 298-14-6

Other potassium compounds - -

Gases

Chemical 

Formula CAS # Weight Percent

Nitrogen N2 7732-18-5

Carbon dioxide CO2 124-38-9

Water H2O 7727-37-9

Other Impurities - -

Ammonia NH3 7664-41-7

Hydrogen cyanide HCN 74-90-8

Carbon monoxide CO 630-08-0

Nitrous oxide NO 10102-43-9

Total mass - - 100.00
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Section 2 of this risk screen summarizes the results of the risk screen for the proposed substitute. The 

remainder of the risk screen is organized into the following sections:

 Section 3: Atmospheric Assessment; 

 Section 4: Potential Health Effects

 Section 5: Occupational Exposure Assessment;

 Section 6: Exposure at End-Use;

 Section 7: General Population Exposure Assessment; 

 Section 8: Volatile Organic Compound Assessment; and

 Section 9: References.

2. SUMMARY OF RESULTS

DSPA fixed generators are recommended for SNAP approval as a flooding agent in normally unoccupied 

spaces. Given that proper training will be provided to personnel and that appropriate personal protective 

equipment (PPE) and proper procedures according to the MSDS (including provisions of adequate 

ventilation) will be used during manufacturing and disposal activities, no significant risks to workers or 

the general population is anticipated. In addition, the risk screen indicates that the use of the proposed 

substitute will be less harmful to the atmosphere than the continued use of Halon 1301 and than other 

substitutes used in this sector, such as HFC-227ea and HFC-125.

Limited end-use, occupational exposure and hazard analyses were conducted since this proposed 

substitute is recommended only for use in normally unoccupied areas. Likewise, no consumer exposure 

and risk screening analyses were conducted since this proposed substitute is intended only for totalflooding applications, which are not used by consumers. Information provided by the submitter, 

summarized in Section 5, indicates that DSPA fixed generators are not likely to pose a significant risk to

workers during the manufacture, installation, maintenance, and cleanup activities. 

3. ATMOSPHERIC ASSESSMENT

This section presents an assessment of the potential risks to atmospheric integrity posed by the use of 

DSPA fixed generators as a flooding agent. The ozone depletion potential (ODP), global warming 

potential (GWP), and atmospheric lifetime (ALT) of the proposed substitute are presented in Table 3. Preactivation, DSPA generator contains no Class I or Class II ODS, nor any compounds with measured 

global warming potential (GWP). Some of the post-activation products and impurities (carbon dioxide, 

carbon monoxide, and nitrous oxide) have a measurable atmospheric impact; however, only very small 

concentrations of those constituents are formed upon activation of DSPA generators and the comparative 

atmospheric impact (e.g., ODP and GWP values of these compounds) to Halon 1301, HCFC Blend A

(NAF S III®), HFC-227ea, and HFC-125 is much lower. Therefore, the use of DSPA generator will be 

less damaging to the atmosphere than continued use of Halon 1301, HCFC Blend A, or other substitutes.
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Table 3. Atmospheric Impacts of DSPA Generator Components Compared to Halon 1301 and 

Other Flooding Agents

Pre-Activation Constituents ODP GWP ALT

Potassium nitrate 0 0 0

Phenol formaldehyde resin 0 0 0

Cyanoguanidine 0 0 0

Post-Activation Products ODP GWP ALT

Potassium carbonate 0 0 0

Ammonium bicarbonate 0 0 0

Potassium bicarbonate 0 0 0

Other potassium compounds 0 NA NA

Nitrogen 0 0 0

Carbon dioxide 0 1 5-200a

Water 0 0 0

Ammonia 0 0

b Few daysb

Hydrogen cyanide 0 0 5-6 monthsd

Carbon monoxide 0 3

e Several monthse

Nitrous oxide 0.017b 298c 114c

Halon 1301 16b 7,140c 65c

HCFC Blend A (NAF S III®) 0.036f 1,444 f NAg

HFC-227ea 0 3,220

c 34.2c

HFC-125 0 3,500c 29c

a

IPCC 3

rd Assessment Report (Houghton et al.2001)

b

Scientific Assessment of Ozone Depletion 2010 (WMO 2011)

c

IPCC 4th Assessment Report (Forster et al. 2007)

d

JACC (2007) 

e MacCarty, et. al. (2007)

f Safety Hitech (2012)

g NA= not available. Atmospheric lifetimes are not given for blends because the components separate in the atmosphere. The 

ALT for HCFC-123 is 1.3 years, HCFC-22 is 12 years, HCFC-124 is 5.8 years, and D-limonene ranges from less than a minute 

to a few hours (IPCC 4th Assessment Report [Forster et al. 2007] and WHO 1998).

4. POTENTIAL HEALTH EFFECTS

According to the MSDS, exposure to DSPA generator may result in irritation if inhalation, ingestion, skin 

contact, or eye contact occurs. According to the MSDS for DSPA generator, if the contents of DSPA 

generator are inhaled, person(s) should be immediately removed and exposed to fresh air. In accordance 

with the MSDS, EPA further recommends that if breathing is difficult, person(s) be given oxygen, 

provided a qualified operator is present, and medical attention be sought. Rescuers should not attempt to 

retrieve victims of exposure to DSPA generator without adequate PPE. A NIOSH/CDC-approved N99 

respirator should be worn to retrieve victims of exposure to DSPA generator. If DSPA generator is 

activated, exposure to aerosol suppression agent through inhalation may cause temporary, mild irritation 

of mucous membrane. If ingestion occurs, person(s) should wash out mouth with plenty of water and not 

induce vomiting. Medical advice should be sought. In case of dermal exposure, the MSDS recommends 

that person(s) immediately wash the affected area with water and remove all contaminated clothing. If 

ocular exposure to DSPA generator occurs, contact lenses, if worn by exposed person(s), should be 

removed. The MSDS for DSPA recommends that person(s) immediately flush the eyes, including under 

the eyelids, with copious amounts of water for 15 minutes (DSPA.nl 2012b). When the PPE 

recommendations outlines in the MSDS for DSPA generators and Section 5 of this risk screen are 

followed, these potential health effects are unlikely to occur. 
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5. OCCUPATIONAL EXPOSURE ASSESSMENT

The potential for occupational exposure to constituents in DSPA generator are examined in this section. 

Specific guidance has been included regarding precautionary measures, PPE, settling rates and re-entry 

time for occupational exposure during manufacture, installation, maintenance, and cleanup. The use of the 

exposure controls and adherence with the appropriate occupational safety guidelines discussed in the 

following sections and the MSDS for DSPA are sufficient to ensure that the manufacture, installation, 

maintenance, and cleanup of DSPA does not pose a significant risk to human health. Further, the 

generator unit consists of solid blocks of DSPA constituents that are not friable and are contained in rigid 

steel casing; as a result, workers have no direct contact with the proposed substitute, and the material is 

prevented from coming into contact with combustible materials during normal transport, storage and 

handling. In addition, exposure to DSPA generator’s raw materials during manual processing at 

manufacture is expected to be in the solid form, with any possible inhalation or dermal exposures 

considered to be negligible (DSPA.nl 2011a). Further, because safety and precautionary measures listed 

in the MSDS for the proposed substitute are to be followed, excessive exposure to workers is unlikely. 

For measures designed to minimize the hazards associated with a specific constituent, the constituent’s 

MSDS should be referenced.

5.1. Occupational Exposure during Manufacture

DSPA generator is not expected to pose a significant risk to workers during manufacture due to the use of 

an automated production process. These workers wear PPE, including suits, safety glasses, and 

respirators. The entire manufacturing space is ventilated with a local exhaust system to reduce airborne 

exposure of pyrotechnical compound.

Currently, there are not any United States-based manufacturing facilities for this proposed substitute and

none are planned. The final product available in United States is the rigid steel case containing solid 

blocks of the extinguishing material. If production were to occur in the United States, the proposed

substitute’s MSDS should be referenced.

5.2. Occupational Exposure during Installation and Maintenance

The extinguishing application density of DSPA generators systems is 50 g/m3for all models. Therefore, 

assuming a safety factor of 1.3, the design application density is 65 g/m3. The post-activation products 

include both gaseous and particulate components, which could cause slight respiratory irritation if inhaled

(DSPA.nl 2011b, EPA 1994). 

Occupational exposure may occur during installation and maintenance of DSPA generators if an 

accidental deployment of a fixed generator occurs. In the event of an accidental discharge, the room 

should be immediately evacuated and the instructions listed in the MSDS for DSPA generator should be 

followed (DSPA.nl 2012b). Worker exposure is unlikely because NIOSH/CDC-approved N99 respirator 

is expected to be worn.
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5.3. Post-activation Cleanup

After DSPA generator is activated, the aerosol is released into the air significantly reducing visibility until 

30 to 40 minutes, when the post-activation particles settle down. According to the submitter and the 

MSDS for DSPA generators, workers should not enter the space following discharge until all particles 

have settled and been ventilated and the gases released by the system have dissipated. If workers must 

enter the space before it has been ventilated, they should wear protective clothing, goggles, and 

NIOSH/CDC-approved N99 respirator. It is unlikely that anyone would enter the space inadvertently 

after discharge, as visibility in the space would be significantly reduced, and signage (indicating that the 

area should not be entered after discharge until ventilation) should be present at the entrances and exits of 

all protected spaces. After 2 hours the air should be refreshed using a ventilator. The settled aerosol

particles can be cleaned up as soon as the structure is totally ventilated or after 24 hours, whichever 

occurs first (DSPA.nl 2011c). In accordance with the MSDS, settled particles are to be collected by hand 

(e.g., with a dustpan and duster) or with a vacuum cleaner. The waste should be collected in suitable 

drums for disposal according to federal, state, and local regulations and the area should be washed clean 

with plenty of water. After activating the generator, slight irritation may occur to the skin due to an 

increase of the pH value. Safety glasses and a NIOSH/CDC-approved N99 respirator, in accordance with 

42 CFR Part 84, should be worn by individuals participating in cleanup procedures because cleanup 

operations are likely to result in the re-circulation of dust particles. Workers cleaning a major spillage 

should wear personal protective clothing (suitable gloves and filter mask FFP-2

1

if dust is formed) 

DSPA.nl 2011c). By adhering to safety guidelines mentioned above and in Section 4, the potential for 

excessive worker exposures to DSPA during post-activation cleanup will be unlikely.

6. EXPOSURE AT END-USE

DSPA generator is not expected to pose significant risk to end-users when used as a flooding agent in 

normally unoccupied spaces. For total flooding applications in normally unoccupied spaces, exposure at 

end-use is only evaluated in the event of an accidental discharge rather than discharge in the occurrence

of a fire. In the event of an accidental discharge at end-use, all personnel should wear NIOSH/CDCapproved N99 respirator and allow adequate time for the aerosol particles to settle and the air to be 

ventilated before re-entering the protected space, as outlined in section 5.2. Individuals responsible for 

cleaning up after inadvertent release of DSPA are expected to follow the cleanup procedures outlined in 

Section 5.3. 

7. GENERAL POPULATION EXPOSURE ASSESSMENT

DSPA generator is not expected to cause a significant risk to human health in the general population 

when used as a flooding agent in normally unoccupied spaces. The generator consists of solid blocks that 

are not friable and are contained in rigid steel casing that would not release into the environment unless 

activated. As discussed in the Background Document, the physicochemical properties of the majority of 

halon substitutes make it unlikely that the substitutes would be released to surface water as a result of use. 

In the case of DSPA generator, it is expected that all of the constituents would rapidly aerosolize during 

expulsion from the container and then settle as a dust on surfaces within the protected space (as opposed 

to becoming airborne and settling on a nearby stream). After settling, cleanup would involve washing or 

rinsing of surfaces. Because all federal, state, and local regulations pertaining to waste disposal are 

followed, no release to the environment is expected.

 

1

FFP-2 is a filtering face piece class that conforms to European standard EN 149 that requires filtering at least 94% 

of airborne particles.
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8. VOLATILE ORGANIC COMPOUND ASSESSMENT

Of the pre- and post-activation constituents of DSPA generator, hydrogen cyanide (a post-activation 

product) is the only compound considered to be a VOC that has not been exempted as a volatile organic 

compound (VOC) under the CAA (40 CFR 51.100(s)). Phenol formaldehyde resin (a pre-activation 

constituent) is also considered a VOC, but is a solid, and therefore not a concern. All remaining 

constituents are not considered to be VOCs. Hydrogen cyanide constitutes a very small percent of the 

post-activation products by weight. In general, VOC emissions should be sufficiently controlled through 

regulations and standard industry practices. VOC emissions from the production of total flooding systems 

charged with DSPA are controlled through standard industry practices, and as such, emissions from 

manufacture of units are likely to be minimal. An assessment was performed to compare the annual VOC 

emissions from use of DSPA in total flooding systems produced in one year to other anthropogenic 

sources of VOC emissions. Assuming that 100 percent of DSPA produced in one year2 were to be used in 

fire occurrences and thus released to the atmosphere (extremely unlikely), only 0.04 MT of VOCs would 

be emitted, which is approximately equal to 8.6x10-6 percent of the annual VOC emissions caused by 

fires,3or only about 1.5x10-6 percent of annual VOC emissions caused by highway vehicles (a major 

source of hydrogen cyanide emissions).

4

 In order to estimate more realistic release rates, data for fire 

occurrences where DSPA may be used would be needed. In the absence of this data, a 100 percent 

release assumption was made. Even at this unlikely release rate, the VOC emissions from use of DSPA

are several orders of magnitude lower than other anthropogenic VOC emissions; therefore, the 

environmental impacts of these VOCs are not considered a significant risk.

 

2 Maximum total production per year at market saturation figure is based on DSPA SNAP submission (DSPA.nl 

2011a).

3 Based on 2010 projections calculated using 2008 EPA annual VOC emissions data for residential wood burning 

and agricultural field burning (EPA 2008 and EPA 2011) and ICF assumptions.

4 Based on 2010 projections calculated using 2008 EPA annual VOC emissions data (EPA 2009) and ICF 

assumptions.
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9. REFERENCES

DSPA.nl. 2011a. SNAP Submission to EPA for DSPA generator. April 28, 2011.

DSPA.nl . 2011b. “Response to Incomplete SNAP Submission for DSPA generator.” July 28, 2011.

DSPA.nl. 2011c. “Response to Incomplete SNAP Submission for DSPA generator.” September 7, 2011.

DSPA.nl. 2012a. “Response to Incomplete SNAP Submission for DSPA generator.” May 16, 2012.

DSPA.nl. 2012b. “Material Safety Data Sheet: DSPA ‘Fixed Installation’ Generator.” March 27, 2012.

EPA 1994. "Risk Screen on the Use of Substitutes for Class I Ozone-depleting Substances: Fire 

Extinguishing and Protection (Halon Substitutes)," U.S. Environmental Protection Agency, 

March 1994.

EPA 2008. 2005 National Emissions Inventory Data & Documentation. Inventory Data: 42 Category 

Summaries. Last updated 6 July 2010. Accessed 20 September 11. Available online at 

<http://www.epa.gov/ttn/chief/net/2005inventory.html#inventorydata>.

EPA 2009. National Emissions Inventory (NEI) Air Pollutant Emissions Trends Data and Estimation 

Procedures.1970 – 2008 Average Annual Emissions, All Criteria Pollutants. Last updated 09 

June 2009. Accessed 20 September 11. Available online at 

<http://www.epa.gov/ttn/chief/trends/index.html#tables>. 

EPA 2011. The National Emissions Inventory. 2008 National Inventory Data. Last updated 19 July 11. 

Accessed 20 September 11. Available online at 

<http://www.epa.gov/ttn/chief/net/2008inventory.html>.

JACC (2007). Cyanides of Hydrogen, Sodium and Potassium, and Acetone Cyanohydrin (CAS No. 74-

90-8, 143-33-9. 151-50-8 and 75-86-5), Volumes I and II. November 2007. Available online 

at:<http://www.ecetoc.org/index.php?mact=MCSoap,cntnt01,details,0&cntnt01by_category=3&c

ntnt01order_by=Number%20Desc&cntnt01template=display_list_v2&cntnt01display_template=

display_details_v2&cntnt01document_id=125&cntnt01returnid=91>

MacCarty, Nordica, Damon Ogle, Dean Still, Dr. Tami Bond, Christoph Roden, Dr. Bryan Willson. 

(2007). Laboratory Comparison of the Global-Warming Potential of Six Categories of Biomass 

Cooking Stoves. Available online at: 

<http://www.scscertified.com/lcs/docs/Global_warming_full_9-6-07.pdf>

OSHA. 1999. OSHA Technical Manual. Department of Labor. Occupational Safety & Health 

Administration. January 20, 1999. Available online at 

<http://www.osha.gov/dts/osta/otm/otm_toc.html>.

Safety Hitech, 2012. NAF S III® Fire Extinguishing Agent. Available online at: 

http://www.safetyhitech.com/en/products/naf-fire-ext-agents/naf-s-iiii